Specialization of neural mechanisms underlying face recognition in human infants

Newborn infants respond preferentially to simple face-like patterns, raising the possibility that the face-specific region, identified in the adult cortex are functioning from birth. We sought to evaluate this hypothesis by characterizing the specificity Of infants' electrocortical responses to faces in two ways: (1) comparing responses to faces of humans with those to faces of nonhuman primates; and 2) comparing responses to upright and inverted faces. Adults' face-responsive N170 event-related potential (ERP) component showed specificity to upright human faces that was not observable at any point in the ERPs Of infants. A putative "infant N170" did show sensitivity to the species of the face, but the orientation of the face did not influence processing until a later stage. These findings suggest a process of gradual specialization of cortical face processing systems during postnatal development

Copolymers of PBT and nylon 4T

Polybutylene terephthalate-nylon 4T copolymers (PBT-PA 4T) are synthesized from the diamide of diaminobutane and dimethyl terephthalate (DMT) with butane diol and more DMT in a concentration range of up to 50% PA 4T. The polymerization conditions were similar to those for PBT: first, a melt polymerization, followed by solid-state post-condensation. The materials were studied by differential scanning analysis (DSC) (melting and crystallization behavior) and dynamic mechanical thermal analysis (DMTA) (glass transitions and torsion moduli). The water absorptions were determined at 100% RH. By increasing the PA 4T content in the copolymers, melting temperatures increased strongly, heats of fusion decreased slightly, and glass transition temperatures increased linearly. The torsion moduli above the glass transition temperature were higher

A Free-Algebraic Solution for the Planar Approximation

An explicit solution for the generating functional of n-point functions in the planar approximation is given in terms of two sets of free-algebraic annihilation and creation operators.Comment: 15 pages, added referenc

Infinite Dimensional Free Algebra and the Forms of the Master Field

We find an infinite dimensional free algebra which lives at large N in any SU(N)-invariant action or Hamiltonian theory of bosonic matrices. The natural basis of this algebra is a free-algebraic generalization of Chebyshev polynomials and the dual basis is closely related to the planar connected parts. This leads to a number of free-algebraic forms of the master field including an algebraic derivation of the Gopakumar-Gross form. For action theories, these forms of the master field immediately give a number of new free-algebraic packagings of the planar Schwinger-Dyson equations.Comment: 39 pages. Expanded historical remark

Hindered Internal Rotation and Ortho-H2 Enrichment in Trans-Stilbene--H2/D2 Complexes

A supersonic free jet expansion has been used to prepare trans-stilbene--H2 and D2 complexes. The cooling in the jet collapses most of the ortho and para H2 and D2 rotational population to the lowest rotational levels of a given nuclear spin symmetry: j = 0 and j = 1. The laser-induced fluorescence excitation spectrum of stilbene--D2 shows a well-resolved doublet at the origin due to stilbene--D2( j = 0) and stilbene--D2( j = 1) complexes. The 4.9 cm-1 splitting of these transitions indicates that the D2 molecule is undergoing hindered internal rotation in the complex and that the barrier to internal rotation changes upon electronic excitation. The relative intensities of the stilbene--D2( j = 0) and stilbene--D2( j = 1) origins depend on the D2concentration in the jet. At low D2 flows the transitions arising from stilbene--D2( j = 1) are favored while at high D2 flows the ( j = 0)/(j = 1) transition intensities approach the 2:1 intensity ratio given by their nuclear spin statistical weights. By contrast, in stilbene--H2 we observe only a single transition at the origin which we assign to stilbene--H2( j = 1). We are able to place an upper bound on the stilbene--H2( j = 0) transition intensity of 5% of the stilbene--H2( j = 1) intensity. Dispersed fluorescence spectra are used to bracket the binding energies of the stilbene--H2/D2 complexes in both ground and excited states

Modeling Studies of the Effects of the Heterogeneous Reaction ClOOCl + HCl → Cl2 + HOOCl on Stratospheric Chlorine Activation and Ozone Depletion

The heterogeneous reaction ClOOCl + HCl → Cl2 + HOOCl was introduced into a chemical trajectory model of the stratosphere. Ten-day trajectories ending at ozonesonde stations at various northern latitudes were run to simulate the period January–March 1994. The reaction on sulfuric acid aerosol surfaces has a negligible effect on ozone chemistry if a sticking coefficient similar to that of ClONO2 + HCl is assumed. On polar stratospheric cloud (PSC) surfaces the chemical effects of the addition of this reaction depend on the fate of proposed product HOOCl: if this species photolyzes to produce either ClO + OH or Cl + HO2, then HCl is activated by the reaction with chlorine peroxide. This heterogeneous activation of chlorine by active chlorine can have a significant effect on Arctic ozone depletion rates in the days following an air parcel\u27s encounter with PSC surfaces. The ozone depletion rate usually increased but in some cases decreased, depending on the extent of PSC processing and on the initial [HCl]/[ClONO2] ratio. Averaged over 3 months, the column ozone loss rates between 350 and 675 K were accelerated by as much as 35% for a set of 10-day trajectories ending at an Arctic station. If, on the other hand, HOOCl decomposes at the surface into HCl and O2, the net effect of these reactions is to convert ClOOCl into Cl2. These species are functionally equivalent, and such a conversion does not perturb the model chemistry

State Mixing and Vibrational Predissociation in Large Molecule Van Der Waals Complexes: Trans‐Stilbene–X Complexes Where X=He, H2, Ne, and Ar

We report a detailed study of vibrational predissociation and intramolecular–intermolecular state mixing in the first excited singlet state of t r a n s‐stilbene van der Waals complexes with helium, hydrogen, neon, and argon. We present evidence that the helium atom in stilbene–He and the H2 molecule in stilbene–H2 possess very low frequency van der Waals bending levels involving delocalization of the complexed species over both phenyl rings. In stilbene–He, the mode‐selective, strong coupling of the out‐of‐plane phenyl ring modes with the pseudotranslation van der Waals modes leads to a dramatic, inhomogeneous broadening of the transitions to several times their breadth in in‐plane vibrations. The observed dispersed fluorescence spectra give product state distributions and internal clock lifetime estimates which can only be made consistent with direct lifetime measurements by assuming extensive state mixing of the intramolecular levels with the van der Waals levels in which the states accessed by the laser are actually only about 30% intramolecular in character. We conclude that in these complexes the processes of intramolecular–intermolecular state mixing (static IVR) and vibrational predissociation are not independent processes but are closely tied to one another. In fact, the vibrational product state distributions observed for the out‐of‐plane phenyl ring levels can best be interpreted as reflecting the percentage van der Waals character in the initially prepared state. In stilbene–H2 the mode selective coupling exhibits itself as a splitting of the out‐of‐plane transitions into a set of 5–6 closely spaced transitions separated by only about 1 cm− 1. The sequence of transitions is suggestive of an in‐plane potential for H2 motion which is nearly flat across the entire length of the stilbene molecule with a small barrier presented by the ethylenic carbons through which the H2 molecule can tunnel. Dispersed fluorescence spectra from these levels point to a two‐tiered coupling scheme with the bound van der Waals levels. In contrast, the out‐of‐plane phenyl transitions in stilbene–Ne and stilbene–Ar possess unusual shifts, but the transitions are narrow once again. In these cases the complexed atom appears to be largely localized over a single phenyl ring

Atmospheric Condensed-Phase Reactions of Glyoxal with Methylamine

[1] Glyoxal reacts with methylamine in drying cloud droplet/aerosol surrogates to form high molecular mass oligomers along with smaller amounts of 1,3-dimethylimidazole and light-absorbing compounds. The patterns observed by high-resolution time-of-flight aerosol mass spectrometry indicate that oligomers form from repeated imine units. The reactions are 1st order in each reactant: rate-limiting imine formation is followed by rapid dimer and oligomer formation. While excess methylamine evaporates from the droplet, half the glyoxal does not, due to self-oligomerization reactions that occur in the absence of methylamine. Glyoxal irreversibly traps volatile amine compounds in the aerosol phase, converting them into oligomers. This is the first reported mechanism for the formation of stable secondary organic aerosol (SOA) material from methylamine, a substance with only one carbon, and could produce as much as 11 Tg SOA yr−1 globally if glyoxal reacts exclusively by this pathway